The present invention relates to an apparatus for containing and dispensing flowable materials, such as for irrigation systems. More particularly, this invention relates to an tank having a sturdy, collapsible, bladder lining the inside of the tank to prevent scaling.
It is known that a good way to transport and store flowable materials is in tanks. This is especially useful for example, in situations when liquid chemicals, such as pesticides, must be transported to a users home or farm.
Mini bulk tanks used in the industry having a capacity of 50-250 gallons (189.4-947.0 liters) are well suited for solutions and emulsifiable liquids but are not generally adaptable to suspension concentrates or flowable formulations, such as chlorothalonil. This is due to a scale which inherently forms within the inner walls of the tanks upon contact with air due to oxidation. The chemical then forms cakes of chemical waste which cannot be used. The viscous liquid clings to the sides of the tank and crusts of scale particles develop which then flake off of the tank. Due to the formation of these scale flakes, the nozzle and screen in the tank dispenser become narrowed which eventually leads to complete nozzle and screen blockage. Therefore, the tank must be cleaned out often or discarded. Thus the tanks do not lend themselves to returnability. Discarded tanks, containing residues of possibly toxic chemicals must be disposed of in special hazardous waste disposal sites and are hazardous to the environment. In addition, the tanks, even if cleaned, cannot be reused for different chemicals due to the possible chemical interaction between any remaining residues of the previous chemical on the walls of the tank and the newly inserted chemical.
Also, the users have a limited amount of space in which to store the materials and the empty containers after they have completed their chemical treatments.
In conventional tanks, plastic linings were melted onto the interior walls of the tank or blow-molded free standing plastic liners were placed inside the tank during its assembly. However, the melted linings were not sturdy and the tanks could not be reused. The blow-molded tanks tended to be expensive and could not be removed from the tank to be cleaned. Also, for gravity flow of the tanks they must be elevated. Therefore, they must be placed on loading docks or trucks, or pedestals had to be built underneath the tanks provide elevation of the tank to remove its contents and fill a measuring device or other suitable container.
For certain tenacious chemicals, such as those used to protect plants from the elements by sticking to the leaves, the evacuation of the tank is difficult due in part to their viscous nature. Therefore, pumps are conventionally used to aid in evacuation of the tank. However, pumps are not reliable and tend to fail thereby wasting time and effort or the users.
Therefore, it is an object of the present invention to provide an apparatus which provides minimal contact of the product with the air over long periods; to provide an apparatus which uses an inner lining or bladder; to provide an apparatus that eliminates the formation of scale and subsequent plugging of the nozzle; an apparatus which can be reused; an apparatus which can be contained and stacked; and an apparatus which is cost efficient and relatively easy to maintain. This object is accomplished by the use of a non-scaling, self-supporting, rigid outer tank fitted with a heavy, durable collapsible bladder. The tank is held in a base and has a cover. In addition, because it is a gravity flow tank, no pump is needed to evacuate the enclosed flowable material.